Production of cadmium sulfide quantum dots by the lithobiontic Antarctic strain Pedobacter sp. UYP1 and their application as photosensitizer in solar cells

Abstract

Background Microbes are present in almost every environment on Earth, even in those with extreme environmental conditions such as Antarctica, where rocks may represent the main refuge for life. Lithobiontic communities are composed of microorganisms capable of colonizing rocks and, as it is a not so well studied bacterial community, they may represent a very interesting source of diversity and functional traits with potential for biotechnological applications. In this work we analyzed the ability of Antarctic lithobiontic bacterium to synthesize cadmium sulfide quantum dots (CdS QDs) and their potential application in solar cells. Results A basaltic andesite rock sample was collected from Fildes Peninsula, King George Island, Antarctica, and processed in order to isolate lithobiontic bacterial strains. Out of the 11 selected isolates, strain UYP1, identified as Pedobacter, was chosen for further characterization and analysis due to its high cadmium tolerance. A protocol for the biosynthesis of CdS QDs was developed and optimized for this strain. After 20 and 80 min of synthesis, yellow-green and orange-red fluorescent emissions were observed under UV light, respectively. QDs were characterized through spectroscopic techniques, dynamic light scattering analysis, high-resolution transmission electron microscopy and energy dispersive x-ray spectroscopy. Nanostructures of 3.07 nm, composed of 51.1% cadmium and 48.9% sulfide were obtained and further used as photosensitizer material in solar cells. These solar cells were able to conduct electrons and displayed an open circuit voltage of 162 mV, a short circuit current density of 0.0110 mA cm−2, and had an efficiency of conversion up to 0.0016%, which is comparable with data previously reported for solar cells sensitized with biologically produced quantum dots. Conclusions We report a cheap, rapid and eco-friendly protocol for the production of CdS QDs by an Antarctic lithobiontic bacterium, Pedobacter, a genus that was not previously reported as a quantum dot producer. The application of the biosynthesized QDs as sensitizer material in solar cells was validated.

Biogenic Sulfur-Based Chalcogenide Nanocrystals: Methods of Fabrication, Mechanistic Aspects, and Bio-Applications

“…According to the well diffusion method results, CdS and ZnS NPs considerably inhibited the growth of these pathogens. Recently, Carrasco et al used the lithobiontic bacterium Pedobacter for the extracellular biosynthesis of spherical CdS NPs of 3 nm in size [126]. Exploited as photosensitizers in solar panels, the as-produced QDs showed similar capabilities as other biogenic QDs [103].…”

“…Besides the previous bio-applications, some studies tested the biogenic S-NPs in other fields. Owing to their electric properties, biogenic S-NPs have been used in solar cells [122,126] and diode fabrication [176]. For instance, CdS/CdSe core/shell QDs synthesized employing E. coli were tested in solar cells as photosensitizer materials and compared with other QDs.…”

“…Core/shell QDs with an average size of 16.7 nm demonstrated improved photovoltaic parameters compared to CdS, and CdTe QDs produced by biological and chemical routes, respectively [122]. Some studies suggest that core/shell NPs produce better results than simple S-based NPs as photosensitizers in solar cells [76,122,126]. Although these NPs worked effectively, the efficiencies are not comparable to materials currently used in the electronic field.…”

Aptamer-Conjugated Quantum Dot Optical Biosensors: Strategies and Applications

“…[ [92][93][94][95] • CdSAg QD production from E. coli [96] • CdTe QD production from E. coli [97] • ZnS QD production from Thermoanaerobacter sp.…”

Biological Synthesis of Nanoparticles: Bacteria

“…When biosynthesized CdS quantum dots were exposed to AgNO 3 concentration, partial replacement of Cd +2 by Ag + led to the formation of significantly stable CdSAg ternary quantum dots hetero-structures. Carrasco et al (2021) accomplished green synthesis of cadmium sulfide quantum dots using an Antarctic lithobiontic bacterium, Pedobacter (family: Sphingobacteriaceae). The bacterial cells were exposed to two experimental sets: 0.0001 M CdCl 2 and 0.001 M cysteine and 0.0002 M CdCl 2 and 0.002 M cysteine.…”